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Re: Which camera settings alter the pixel data of raw files?

As a newcomer to the magazine & seriously wanting to learn more, I am getting a lot from reading areas that I was not even aware of. But, surely I cannot be the only newcomer, couldn't the magazine have a section for beginners & how to improve, I have learnt so much via the forum, but it would be good to read it in the magazine.

Re: Which camera settings alter the pixel data of raw files?

Re: Which camera settings alter the pixel data of raw files?

I used to think that RAW consisted of the actual levels a pixel "saw", but it cannot be that simple. The pixels are filtered to one colour (R,G or B) and therefore there is at least one level of calculation which has to "fill in" the colour for, say, a red-filtered pixel for its green and blue values by looking at the neighbours. Then there is the dark level which has to be subtracted, to get rid of one level of noise, and then there is some (possible) additional noise filtering especially for high ISO. So there is quite a bit of calculation that seems to be done even for RAW images.

Re: Which camera settings alter the pixel data of raw files?

Originally Posted by neonlamp

I used to think that RAW consisted of the actual levels a pixel "saw", but it cannot be that simple. The pixels are filtered to one colour (R,G or B) and therefore there is at least one level of calculation which has to "fill in" the colour for, say, a red-filtered pixel for its green and blue values by looking at the neighbours. Then there is the dark level which has to be subtracted, to get rid of one level of noise, and then there is some (possible) additional noise filtering especially for high ISO. So there is quite a bit of calculation that seems to be done even for RAW images.

All of which is only done in camera when set for JPEG output otherwise it's done later in the conversion software. A raw file is a data file not an image file - it only becomes an image file when run though software such as DPP or Adobe Camera Raw or similar. This is why a raw file can be reprocessed many different ways with far less degradation than a JPEG or TIFF, unlike those files the luminosity data is as recorded off the sensor, not fixed as colour channels, and can be non-destructively recalculated over and over again for different exposures, white balance noise etc. Once converted to a 3-channel image these values are effectively fixed and subsequent manipulation is more limited as extreme changes can degrade the data by over compressing, over expanding or adversely biasing the data leading to unwanted artefacts.

This is not to say that raw files have unlimited leeway - if you over or under expose 3 or 4 stops for instance and try to pull it back you will get noise and colour distortion issues. Raw capture is not an excuse for bad technique but a way of refining the output according to your requirements not those of the firmware engineer who created the various picture style presets...